The chemical resistance of high-density polyethylene geomembranes (GMs) with smooth and textured surfaces in notched and unnotched forms at different values and in the range of 20-80 degrees C was examined with stress crack resistance testing. Surface microcracks in GMs were observed in scanning electron microscopy images. Smooth and textured GMs did not show significant differences in their mechanical behaviors. The yield strength decreased with the temperature, pH, and exposure time. The yield strain increased with the temperature, but there were no good correlations with pH values. The break strength also decreased with the temperature and showed no significant correlation with pH variations. The break strain did not show a good correlation with the temperature and pH variations. The stress crack resistance was independent of pH variations but significantly depended on the temperature. It was negatively correlated with the exposure time. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 2575-2582, 2010